Agent Skills: Test Reviewer

Test Reviewer

Audience: Developers reviewing test suites for quality and completeness.

Goal: Analyze automated tests for coverage completeness, assertion quality, and adherence to testing best practices.

Review Steps

1. Identify Test Context

• Run git status and git diff to identify changed files and their corresponding test files
• Use Grep and Glob to locate test files related to the changed code
• Identify the testing framework (RSpec, Minitest, Jest, Playwright)

2. Map Implementation to Tests

• Read the implementation files being tested
• Identify all public methods, endpoints, and behaviors that should have test coverage
• Create a coverage matrix mapping implementation features to test cases

3. Analyze Test Coverage

For each implementation feature, check if tests exist for:

• Happy Path: Normal successful execution flows
• Sad Path: Error conditions, validation failures, edge cases
• Boundary Conditions: Empty values, nil/null, maximum limits
• State Transitions: Before/after states, side effects
• Authorization: Permission checks (if applicable)
• Integration Points: External service calls, database operations

4. Evaluate Test Quality

• Assertion Quality:
  • Are assertions specific and meaningful?
  • Do tests verify behavior, not implementation?
  • Are error messages helpful for debugging?
• Test Isolation:
  • Do tests depend on execution order?
  • Are external services properly mocked?
  • Is test data properly set up and torn down?
• AAA Pattern:
  • Clear Arrange (setup) section
  • Single Act (execution)
  • Focused Assert (verification)
• Test Names:
  • Do names describe expected behavior?
  • Would someone understand the test without reading code?

5. Check Test Patterns

• Framework Compliance:
  • RSpec: Proper use of describe, context, it, let, before
  • Minitest: Proper use of setup, test, fixtures
  • Jest: Proper use of describe, it, beforeEach, mocks
• Project Conventions:
  • Do tests follow existing patterns in the codebase?
  • Are shared examples/contexts used where appropriate?
  • Is test data handled consistently (fixtures vs factories)?

6. Identify Missing Scenarios

Look for common gaps:

• Nil/Empty Handling: What happens with nil, empty strings, empty arrays?
• Error Cases: Network failures, database errors, validation failures
• Concurrency: Race conditions, parallel execution
• Edge Cases: First/last items, exactly at limits, off-by-one
• Security: Input sanitization, authorization bypasses
• Performance: Large data sets, timeout scenarios

7. Check for Test Anti-Patterns

• Skipped/pending tests without justification
• Tests with sleep or hardcoded delays (flaky test smell)
• Tests with non-deterministic data (random values without seeds)
• Over-reliance on allow_any_instance_of or similar broad mocks

Note: This skill performs static analysis only. Test execution is handled separately to avoid redundant test runs.

Red Flags to Watch For:

• Tests that always pass (no real assertions)
• Tests that test Rails/framework behavior, not application code
• Overly complex test setup indicating design issues
• Mocking too much (testing mocks, not real behavior)
• No error case coverage
• Tests tightly coupled to implementation details
• Missing database state verification
• Frozen fixture assertions: Exact collection comparisons (assert_equal [a, b], scope or expect(scope).to eq([a, b])) that break when unrelated fixtures are added. Recommend assert_includes/expect(...).to include(...) instead.

Test Quality Review Report

Provide your findings in this structure:

Test Coverage Summary

• Implementation Files Reviewed: [count]
• Test Files Reviewed: [count]
• Coverage Gaps Identified: [count]
• Quality Issues Found: [count]

Coverage Matrix

| Feature/Method | Happy Path | Sad Path | Edge Cases | Status | |----------------|------------|----------|------------|--------| | [method_name] | pass/fail | pass/fail| pass/fail | [Complete/Gaps] |

Critical Coverage Gaps

[List features/methods with missing test coverage, prioritized by risk]

1. [Feature/Method Name] - [file:line]
   • Missing: [what scenarios are not tested]
   • Risk: [why this gap matters]
   • Recommended: [specific test to add]

Test Quality Issues

High Priority:

• [Issue description with file:line reference]
• Recommendation: [how to fix]

Medium Priority:

• [Issue description]
• Recommendation: [how to fix]

Low Priority:

• [Issue description]
• Recommendation: [how to fix]

Missing Edge Cases

[List specific edge case scenarios that should be tested]

1. [Scenario]: [why it matters] → [file to add test]

Pattern Violations

[Tests that don't follow project conventions or best practices]

Recommendations

1. [Prioritized actionable recommendations]
2. [Include specific test examples where helpful]
3. [Reference project patterns to follow]

Overall Assessment

• Test Suite Health: [Excellent/Good/Needs Work/Critical Gaps]
• Confidence Level: [High/Medium/Low] - Can we ship with current tests?
• Priority Actions: [Top 3 things to fix before merging]

Note: All file paths should be absolute. Focus on actionable feedback that improves test quality and coverage.